DIY frame rail reinforcement... - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 05-19-2008, 01:55 PM   #21
Elite Member
iTrader: (13)
 
Join Date: Nov 2006
Location: Tigard, Oregon
Posts: 3,908
Total Cats: 0
Default

I've been wondering why more people haven't tried something like this. I was thinking about using angle iron on either side of the rail. Bolt them through the floor and to each other through the rail.
cueball1 is offline   Reply With Quote
Old 05-19-2008, 02:02 PM   #22
Elite Member
iTrader: (5)
 
Atlanta93LE's Avatar
 
Join Date: Sep 2006
Location: Marietta, GA
Posts: 2,198
Total Cats: 1
Default

Quote:
Originally Posted by 91NApeewee View Post
thats cool, but the point of the FM rails is that they mount to the floor pans increase the stiffness along them.
Hit the nail on the head here. While these aluminum rails might do something, they certainly won't provide the same rigidity as the FM rails. You really need a hat-shaped section in order to attach top the floor, rather than a C-shaped channel. Remember...the end goal should be closed sections.
Atlanta93LE is offline   Reply With Quote
Old 05-19-2008, 02:40 PM   #23
Junior Member
 
Join Date: Dec 2007
Location: San Diego to LA, CA
Posts: 297
Total Cats: 0
Default

Quote:
Originally Posted by Atlanta93LE View Post
Remember...the end goal should be closed sections.
closed sections are not subject to Lateral Torsional Buckling . Damn structural engineering.

But yea, it needs to somehow hold to the floor. Incorporate some L brackets maybe
91NApeewee is offline   Reply With Quote
Old 05-19-2008, 02:52 PM   #24
Elite Member
iTrader: (46)
 
Stein's Avatar
 
Join Date: Dec 2007
Location: Nebraska
Posts: 4,812
Total Cats: 138
Default

Quote:
Originally Posted by cueball1 View Post
I've been wondering why more people haven't tried something like this. I was thinking about using angle iron on either side of the rail. Bolt them through the floor and to each other through the rail.

I see where you are going with this, but I think the fact that each "half" is tied together benefits you too much to not go with a couple of hat-shaped sections like the FM ones. Wouldn't be that expensive to have a metal fab place shear them up and put them in a brake for four bends. Plus, the will likely be lower weight as well, even without the cutouts on the FM ones. Hell, you can probably hole saw some holes if you want to lower the weight. They are probably saving 2 lbs is all. Bolted wide through the floor is key here.
Stein is offline   Reply With Quote
Old 05-19-2008, 03:29 PM   #25
Elite Member
iTrader: (5)
 
Atlanta93LE's Avatar
 
Join Date: Sep 2006
Location: Marietta, GA
Posts: 2,198
Total Cats: 1
Default

Quote:
Originally Posted by 91NApeewee View Post
closed sections are not subject to Lateral Torsional Buckling . Damn structural engineering.
Well, they are more resistant to LTB, but they can exhibit that failure mode, especially with highly slender, nonuniform elements. I can show you some photos of it happening if you like

Good to see another structural engineer here. I do structural forensics for a living.
Atlanta93LE is offline   Reply With Quote
Old 05-19-2008, 03:45 PM   #26
Junior Member
 
Join Date: Dec 2007
Location: San Diego to LA, CA
Posts: 297
Total Cats: 0
Default

Quote:
Originally Posted by Atlanta93LE View Post
Well, they are more resistant to LTB, but they can exhibit that failure mode, especially with highly slender, nonuniform elements. I can show you some photos of it happening if you like

Good to see another structural engineer here. I do structural forensics for a living.
I believe you, lol. I was going off the frame rail lengths not being slender. I assumed their slenderness ratio would not allow LTB to govern.

also, you have a PM
91NApeewee is offline   Reply With Quote
Old 05-19-2008, 04:02 PM   #27
Elite Member
iTrader: (9)
 
Join Date: Aug 2006
Location: Concord, North Carolina
Posts: 4,173
Total Cats: 5
Default

Quote:
Originally Posted by samnavy View Post
How did you hurt your frame rails that bad in the first place?
Low + Speed bumps...mine look like a domestic violence victim.
miatamania is offline   Reply With Quote
Old 05-19-2008, 04:34 PM   #28
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

Quote:
Originally Posted by miatamania View Post
Low + Speed bumps...mine look like a domestic violence victim.
Same here. The driver's side one is really bad.
ZX-Tex is offline   Reply With Quote
Old 05-19-2008, 04:46 PM   #29
Elite Member
iTrader: (13)
 
Join Date: Nov 2006
Location: Tigard, Oregon
Posts: 3,908
Total Cats: 0
Default

+1 on the lowered vs speedbump problem.
cueball1 is offline   Reply With Quote
Old 05-19-2008, 05:02 PM   #30
Elite Member
iTrader: (39)
 
Zabac's Avatar
 
Join Date: Sep 2007
Location: High Point NC
Posts: 4,854
Total Cats: 8
Default

Mine suffered when I tried to grind a curb skater style :(
Zabac is offline   Reply With Quote
Old 05-19-2008, 06:07 PM   #31
Elite Member
iTrader: (24)
 
Join Date: Jun 2007
Location: Sherman Oaks, CA
Posts: 4,481
Total Cats: 3
Default

ah screw you guys.... every week you disappoint me by making good **** from useless crap :/

kind of makes me want to hang myself for spending all that precious $$ :/
UrbanSoot is offline   Reply With Quote
Old 05-19-2008, 07:12 PM   #32
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2008
Location: Ventura, CA.
Posts: 220
Total Cats: 0
Default

Quote:
Originally Posted by samnavy View Post
What exactly did that entail?
I can see some grinder work and perhaps some hammering. Was it that the rail was slightly wider than the track in the bracing, or was your rail uneven down it's length and you just smoothed it out.

How did you hurt your frame rails that bad in the first place?
What is the width of the rack you're using?

Do you think that these braces would "slip" over an unmolested frame rail?
What would be ideal is if the brace .001" wider than the rail and you would simply tap it up into place with a rubber mallet. Rigging up a crossbrace would be a really simple proposition.

Is there any dramatic difference in the undercarriage between the years. I know FM's brace is "universal", but is there anything to consider along those lines?
1. The massaging was a bit of hammering and a wire wheel. The rail was squished from previous owner probably using it as jacking points...also the rails had a whole bunch of spray undercoating on them (I shipped the car over from Hawaii)
2. Yes they would just slip over if they haden't been so bent outta shape. Light tapping with a rubber mallet worked on another miata that did same project.
3. Pretty sure the undercarriage is similar...the only thing to watch out for is fuel + brake lines.
MX54PLA is offline   Reply With Quote
Old 05-19-2008, 07:23 PM   #33
Elite Member
iTrader: (5)
 
Atlanta93LE's Avatar
 
Join Date: Sep 2006
Location: Marietta, GA
Posts: 2,198
Total Cats: 1
Default

Look into the test method FM did to quantify the stiffness increase from their rails (on their site I believe). Do the same test with your car. Compare results.
Atlanta93LE is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
In need of base map for stock 1997 brandonbkd MEGAsquirt 0 09-29-2015 12:52 AM
3rd Time's a Charm...hopefully. zephyrusaurai Meet and Greet 2 09-28-2015 11:59 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 12:44 AM.